The present invention relates to an air gun for the production of non-woven fabric as a non-woven fabric producing apparatus, particularly to an air gun and a manufacturing apparatus of the type wherein filaments as spun from spinning nozzles are taken up at high speed and delivered onto the surface of a collector such as a screen belt while being carried by an air stream.
Generally, as a non-woven fabric producing apparatus, particularly a non-woven fabric producing apparatus of the type wherein filaments as spun from spinning nozzles are taken up and delivered onto a screen belt while being carried by an air stream to form non-woven fabric (web) , there is known the apparatus shown in FIG. 8.
In such non-woven fabric producing apparatus, filaments 2 as spun from spinning nozzles 1 are taken up and delivered onto a screen belt 3 while being carried by an air stream to form non-woven fabric. The filaments 2 from the spinning nozzles 1 are first received into an inlet of an air nozzle 7. The air nozzle 7 is provided sideways with a compressed air inlet 6, and by compressed air supplied from the compressed air inlet 6 the filaments 2 are discharged in an outlet direction of air.
In the outlet direction of the air from the air nozzle 7, namely, in the filament discharging direction there are disposed the accelerator tube 8a connected to the air nozzle 7 and a guide tube 8b connected to the tube 8a. The filaments 2 pass through these tubes 8a and 8b while being carried by the air. To the front end of the guide tube 8b is connected a separator nozzle 9. The guide tube 8b is for conducting the filaments 2 from the accelerator tube 8a to the separator nozzle 9 together with compressed air and diffusing them toward the screen belt 3. The filaments 2 are dispersed to an appropriate degree by the separator nozzle 9 and are deposited on the screen belt 3, so by moving the screen belt 3 there is formed non-woven fabric.
There is also known a fibrous web forming process which is described in Japanese Patent Laid-Open No. 151357/85. According to this process, a multifilament yarn is forced to impinge on an impingement plate together with compressed air from an elongated tube and the multifilament yarn thereby disintegrated is collected in the form of sheet onto a conveyor, the compressed air being discharged forcibly from near the lower portion of the said elongated tube in a direction away from the multifilament yarn jet direction.
In the production of non-woven fabric according to such spun bond process, it is required to thin the filaments in order to improve the productivity and quality. To this end, heretofore there have been adopted 1 a method wherein the air pressure supplied to the air gun is raised to increase the flow rate of air, thereby pulling the filaments strongly, 2 a method of shortening the distance (spinning distance) from the spinning nozzle to the air gun, 3 a method of reducing the volume of filament discharged from each of many spinning nozzles, and 4 a method of increasing the spinning temperature. But in the case where productivity is the principal object, the above methods 1 and 2 are usually adopted.
However, according to the method 1, as the flow rate of air increases, the filaments are disturbed when discharged from the separator nozzle, resulting in variations in the shape of non-woven fabric deposited on the screen belt and the uniformity of the non-woven fabric being deteriorated. Further, the increase in the flow rate of air causes an increase of the running cost and an increased cost of the product obtained results. Also, the method 2 involves a problem from the standpoint of stable spinning and it is difficult to practice this method.